Although a telescope is mainly used for observing an enlarged image of a distant object, when a vibration is transmitted to the telescope by a so-called “hand-shake”, the image is vibrated to become difficult to be observed. As for the measures against a hand-shake, for example, a large number of vibration reduction lenses for cameras are developed (for example, see Japanese Patent Application Laid-Open No. 2-234115). Moreover, telescopes equipped with a vibration reduction function are developed (for example, see Japanese Patent Application Laid-Open No. 10-186228).
However, the vibration reduction telescope disclosed in Japanese Patent Application Laid-Open No. 10-186228 does not disclose how to carry out focusing. Even if focusing is carried out by moving a vibration reduction lens having negative power along the optical axis, there has been a problem that the mechanism becomes terribly complicated. On the other hand, configuration of the vibration reduction lens for a camera disclosed in Japanese Patent Application Laid-Open No. 2-234115 does not include an erection prism, which is indispensable for a telescope, so that there has been a problem that it cannot be used as an objective lens of a telescope.